As Facebook builds its ads business and gives advertisers more ways to reach different audiences, a new lexicon has emerged.

The social network has invented terms like Sponsored Stories, Page Post Ads and Promoted Posts, but it doesn’t always explain them or maintain consistent usage over time, especially since the same ads serve different levels of advertisers, who purchase them through varying channels.

Here we’ll break down the main categories of Facebook ads that appear in News Feed and the desktop sidebar: Sponsored Stories, Page Post Ads, Promoted Posts and Marketplace Ads. Understand the difference in what the units look like, how they are purchased, who they can be shown to and what goals they achieve.

Sponsored Stories

Sponsored Stories are built around user activity. Advertisers simply pay to highlight an action that users have already taken on the social network or within a Facebook-connected app. That action is shown to a user’s friends, either in the sidebar or in News Feed. Sponsored Stories cannot be used to reach an audience that is not connected to the page or app through a friend.

Advertisers do not have any creative control over these ad types because they are generated from an organic user action. They might also include a page or app’s current profile photo.

The most common Sponsored Stories are “Page Like” stories, but advertisers can sponsor check-ins, offer claims, Likes on individual posts, or any custom Open Graph action. For example, Doritos has sponsored stories about when users “vote for a finalist” in its Crash the Super Bowl app.

Companies can also sponsor stories about when users share links from their domain. For example, when a user posts an Amazon link on Facebook, Amazon pays to show that story to more of a user’s friends, as seen to the right.

The goal of Sponsored Stories to get more users to take the same action that a friend has. If a page wants Likes, it can show Page Like Sponsored Stories. If a retailer wants more users to claim an offer, it can show Offer Claimed Sponsored Stories. If a company wants more sweepstakes entries in its custom Open Graph app, it can create Sponsored Stories about users “entering a sweepstakes.”

Most Sponsored Stories can be created through the self-serve ad tool, Power Editor or API, however, Open Graph Sponsored Stories require advertisers to work with a third-party provider that has access to the API.

Sponsored Stories have been around since January 2011, but when Facebook first began using the term, it also encompassed what later became known as Page Post Ads. The change has led to some lingering confusion, but ads that are directly derived from page posts are no longer considered Sponsored Stories. We’ll discuss Page Post Ads in the next section. The defining factor of Sponsored Stories to remember is that they are paid promotion of organic user activity.

Page Post Ads

Page Post Ads are advertisements that begin as posts on a fan page but get additional paid distribution among fans, friends of fans, or non fans within News Feed or the sidebar, as a result of creating campaigns in Facebook’s ad tool, Power Editor or API.

Page Post Ads can be links, photos, videos, offers, events, questions or statuses, allowing for a lot of creative freedom. And unlike Sponsored Stories and Promoted Posts, these ads can be shown to anyone on Facebook, even if users are not connected to the page themselves or through a friend.

Page Post Ads are ideal for engagement and content marketing, as well as promoting events and offers, but they are not always as effective for fan acquisition. For example, a Page Post Ad might give users the option to play a video, like the video, comment on it and share it, in addition to the option to Like the page itself. This is different from Sponsored Stories, which give users one clear call to action.